1. Technical Field
The present invention relates to an execution method of a position calculating circuit, which calculates the position by receiving a satellite signal transmitted from a positioning satellite, and the like.
2. Related Art
A GPS (global positioning system) is widely known as a positioning system using a positioning signal and is also used as a position calculating circuit built into a mobile phone, a car navigation apparatus, or the like. The position calculating circuit performs position calculation processing for calculating the three-dimensional coordinate values, which indicate the position of the position calculating circuit, and a timepiece error on the basis of the information, such as the positions of a plurality of GPS satellites or a pseudo distance from each GPS satellite to the position calculating circuit.
As such a position calculating circuit has come into wide use, the application range of the position calculating circuit has also expanded. That is, the position calculating circuit is increasingly being mounted in products (electronic apparatuses) other than a product (electronic apparatus) whose main purpose is to indicate the position for the user. For example, a technique is known in which a position calculating circuit is mounted in a digital camera and the photographing location is recorded corresponding to a photographed image. In an electronic apparatus which mounts a position calculating circuit therein, a processor which performs overall control of the electronic apparatus is generally provided. In general, transmission of the position data from the position calculating circuit to the processor of the electronic apparatus is performed whenever the position calculating circuit calculates the position or at predetermined intervals (for example, every one second).
However, if the output interval of the position data is short, interruption processing should be frequently performed on the processor side. In this case, a problem occurs in that the processing load increases. As a technique for solving this problem, JP-A-2007-156856 discloses a technique of setting long the output interval of the position data from a position calculating circuit.
As described above, generally, the known position calculating circuit is configured to supply the position data actively to the processor of the electronic apparatus. In other words, this means that the processor of the electronic apparatus acquires the position data passively from the position calculating circuit. Accordingly, for example, even at a timing at which the position data is needed, the position data is not always input from the position calculating circuit to the processor of the electronic apparatus. Thus, there was a constraint on the acquisition of data in that the input of the newest position data from the position calculating circuit should be waited for. Similarly, although the position calculating circuit can calculate not only the position but also various kinds of information, such as the time and the moving speed, there was the same problem regarding the acquisition of these data items on the processor side of the electronic apparatus.
In addition, the position calculating circuit may be configured such that not only the position data but also data other than the position data, such as the time data, is acquired by performing the position calculation. In this case, in the technique disclosed in JP-A-2007-156856, it is necessary to supply the data to the processor of the electronic apparatus by performing communication interrupt whenever the position calculating circuit acquires a plurality of kinds of data. Accordingly, even if the interval of data output from the position calculating circuit is set to be long, the communication load per position calculation is not reduced. This was not sufficient in terms of the reduction of power consumption.